We have trouble with Black Fly all over an Elderberry Tree we have. We can't get to all of it, and don't want to use nasty chemicals, but find we can keep the bits we can get to clear by spraying a weak solution of water with washing up liquid on them with a small handheld plant spray gun. Apparently the soap breaks down a coating they have and stops them breading.
Security Was it near a ferry port? Maybe showing the boot hadn't been opened since checked. Or When visiting a contract manufacturing supplier in Hungary many years ago that also made millions of mobile phones they sealed our bags with something similar to an event wristband to show we couldn't have slipped a mobile in there whilst nobody was watching. They also security tagged our own phones and Laptops to show we'd taken them in.
I just did a google search on aphids / Black fly & Cherry trees... I didn't know ants played a role... Preventive Action (Ant Management): Ants transport aphids and protect them from predators. Apply grease bands or a physical barrier (like Vaseline) around the trunk in early spring to stop ants from reaching the canopy.
I can remember years when aphids affected the crop, but it hasn't happened for around a decade here, so luck of the draw. The stunning blossom on ours is slowly lessening over the years, but it is as old as me. I had a mate with a row of fig trees near guildford, and the crop was ruined each year, without fail by wasps. Even if you found a relatively unscathed example, there was still at least one inebriated wasp revealed when cut open.
I had an Irish terrier in my youth as did my late father, currently iv two wire fox terriers ( Irish are just so hard to find)
Not quite what they hoped for when they booked him and said..... "We want you to bring the house down"